A technique of estimating the own position of a mobile body has been developed which includes: sensing surroundings of the mobile body with a camera and a laser rangefinder mounted in the mobile body; and acquiring the position on a map and an attitude angle of the mobile body by matching the sensing results with the map. A conventional example of this technique is disclosed in Japanese Patent Application Publication No. 2008-250906.
In the own position estimation technique of Japanese Patent Application Publication No. 2008-250906, past records of sensing results and movement amounts calculated by using wheel speed pulses, a gyroscope, and the like are accumulated in association with each other, and the position and the attitude angle of the mobile body are estimated with adjustment made such that the accumulated data and the map match each other. Moreover, in the own position estimation technique of Japanese Patent Application Publication No. 2008-250906, use of the records of sensing results acquired within a fixed distance at all times enables stable estimation of the own position of the mobile body by eliminating influence of the movement speed of the mobile body.
In the conventional own position estimation technique described above, however, the use of the records of sensing results acquired within the fixed distance poses a problem that, in a situation where a detection error in the movement amount increases, deviation between the sensing results and the map increases so much that the estimation of the own position becomes difficult.